A mod_perl developer is responsible for creating, maintaining, and enhancing websites and web applications using the mod_perl module of the Apache HTTP server. They work with Perl programming language and Apache server to develop dynamic web content and server applications. Their duties include writing efficient code, debugging, testing, and problem-solving. They also optimize web applications for maximum speed and scalability. Additionally, they collaborate with front-end developers and web designers for web design features, ensuring high performance and responsiveness. They also ensure the security and data protection of web applications and adhere to best practices in coding and scripting.